Most boat builders wire the starter their own way, so even though Lehman may recommend a wiring diagram, there is no way to know if they did it that way. But here is a diagram that I think is pretty generic to go by:

Many builders do not use a neutral switch so in that case just assume that the wire to the starting switch is continuous. Or that switch could be in the circuit from #5 on the key switch to the starting button on some installations. Or the starting button could be part of the key switch. Also Lehman engines have a starting solenoid as part of the starter. But even if they do it is very common to have a starting relay as shown in the diagram between the starting push button and the on starter solenoid, so it looks just like the diagram above.

Wiring diagram attached. Starter is standard Bendix type. Pinion shaft has a tendency to rust so if starter spins but won't engage whack it with a rubber hammer. Solenoid relay is generic and cheap so it's a good idea to keep a spare onboard. There is also a circuit breaker that must be turned on to energize switch, volt meter, and low oil buzzer. I suspect most neutral safety switches are disconnected.